The compound d-2-(6-methoxy-2-naphthyl)-propionic acid (naproxen, International Non-proprietary Name) is known from the literature for its excellent antiinflammatory properties. It was first described in U.S. Pat. No. 3,904,682. Several methods for its preparations are known which contemplate the synthesis of a racemic mixture of the d- and l-2-(6-methoxy-2-naphthyl) propionic acids (see for instance U.S. Pat. Nos. 3,658,863; 3,658,858; 3,663,584 and 3,694,770) which is subsequently resolved into the two optically active antipodes through formation of salts with optically active organic bases (see e.g. French publication No. 2,035,846 and U.S. Pat. No. 3,683,015). On the other hand, few methods are known, which deal with the synthesis of racemic mixtures of the d- and l-2-(5-halo-6-methoxy-2-naphthyl)-propionic acids, their resolution into the optically active antipodes and the final dehalogenation of the d-isomer to the desired end product. British Pat. Nos. 1,274,271; 1,274,272 and 1,274,273 describe for instance the synthesis of compound II as a racemic mixture but no example is given as to the resolution of said mixture into the optically active antipodes and to the dehalogenation of d-isomer either.